Lattice QCD signal for a bottom-bottom tetraquark

TL;DR

This paper presents lattice QCD evidence for a bound bottom-bottom-light-light tetraquark state, identifying a specific quantum channel with a small but significant binding energy, advancing understanding of exotic hadrons.

Contribution

It introduces a novel lattice QCD and quark model framework to study heavy-heavy-light-light tetraquarks and identifies a potential bound state in the scalar isosinglet channel.

Findings

Bound state found with 1.8-3.0 sigma confidence

Binding energy estimated at 30-57 MeV

Only the scalar isosinglet channel shows binding

Abstract

Utilizing lattice QCD results for the potential of two static antiquarks and two dynamical quarks as well as quark model techniques for the dynamics of two heavy antiquarks in a cloud of two light quarks, we are provided with an accurate framework for the study of possibly existing heavy-heavy-light-light tetraquarks. Among the possible quantum numbers of such a system, we find binding in only one channel, the scalar isosinglet. Solving the Schroedinger equation for the displacement of the heavy antiquarks and taking systematic errors into account, we find an antibottom-antibottom-light-light bound state with a confidence level of around 1.8 sigma ... 3.0 sigma and binding energy of approximately 30 MeV ... 57 MeV.